Patent GB-133337-A (GB)
IPC: H04Q3/42
Abstract: 133,337. Western Electric Co., and Polinkowsky, L., (Western Electric Co. partly). Dec. 17. 1917. Semi-automatic exchange systems.-In a system in which calls are extended from a manual A-operator to a B-operator who selects the wanted subscriber over automatic switches, and in which the numerical selection is initiated by the B-operator and is controlled by the insertion of the plug in the jack on the A-board, the B- operator may force the release of the switches whether or not the plug has been inserted by the A-operator. If the wanted line is found busy, the switch on the incoming end of the junction line is held in a position in which al flash signal is given to the A-operator. The B-operator is provided with a single set of keys and with three register sets, with one of which the keyboard and the incoming trunk are connected on the depression of an assignment key individual to the trunk. Preference is given to one register set, and when this is busy, to a second register set, and all three register sets are made busy as long as any one of them is connected with the keyboard. The invention is described as applied to a system in which a manual A-operator, shown to the left of Fig. 1, extends a call over the junction 270, assigned by the B-operator, to the group-selector shown on the right of Fig. 1. The depression of the assignment key 203 causes the sequence switch 251 to select an idle one of the three registers, parts of which are shown within the dotted rectangles in Fig. 2, the remaining parts of one register, together with the keyboard common to all three registers, being shown in Fig. 3. Selection of idle register set. The depression of the assignment key 203, individual to the assigned junction 270, energizes a relay 204 which moves the sequence switch 206 into its second position, in which a second sequence switch 251 searches for an idle register set under control of the test relays 212, 213. During this time, a guard lamp 218 is flashed by an interrupter 219 and a busy lamp 216 is continuously lighted over contact 221. The searching sequence switch starts from the position in which it was left from the previous call, and, as it rotates, contact 252 is intermittently grounded between each stopping position, thereby preparing a circuit through the right-hand high-resistance winding of the test relay 213, which is connected over contact 214 to the contacts 253, 258, 259 of sequence switch 251. Connexion can be obtained with register set A in positions 1 4, 7, 10 of the switch 251, with register set B in positions 2, 5, 8, 11, and with register set C in positions 3, 6, 9, 12, preference being given to set A when this is idle, or to set B when set A is busy. When a register set is taken into use, the other registers are made busy until the number keys have been depressed. Assuming that all three register sets are free, just before the switch 251 reaches any of the positions 1, 4, 7, or 10 the circuit of the test relay 213 is completed over contact 253, wire 390, relays 311, 312 (individual to set A), contact 313 of sequence switch 310 (individual to set A), back contact of relay 349 (individual to set C), and contact 338 of sequence switch 330 (individual to set B). Relays 213, 311, 312 are all energized. Relay 311 moves the sequence switch 310 into its fifth position, and relay 312 energizes a relay 316 which connects battery to the relays 312, 311 so that these relays remain energized after contact 313 is opened by the movement of switch 310 into its fifth position. The left-hand highresistance winding of relay 311 is also connected in parallel with relay 312, the resistance of which is low enough to keep relays 213, 212 energized in case 'contact 313 opens before switch 206 reaches its fourth position. Relay 213 energizes relay 212, which arrests the switch 251 and moves the switch 206 into its fifth position, in which contact 221 directly grounds the lead 390, thereby short-circuiting the relay 316, which disconnects relay 312, leaving relay 311 energized over its two windings in series. In the fifth position of switch 206, the busy lamp 216 is flashed by the interrupter 219, and the guard lamp 218 is connected to the back contact of relay 229, so that it glows unless the A-operator has inserted the plug. If, however, the register set A is in use, and set B is idle, when the switch 251 is searching for an idle set, the circuit of the test relay 213 will be completed in one of the positions 2, 5, 8, or 11 over contact 258, wire 395, relays 331, 332, contact 333 of switch 330 (individual to set B), contact 321 of switch 310 (individual to set A), and contact 348 of switch 340 (individual to set C). Relays 213, 331, 332 are energized and operate as before. If set A becomes free after set B has been seized, the opening of contact 321 is without effect on set B after relay 336 has closed its contact, but set A is made inaccessible until the switch 330 of set B moves into its seventh position (i.e. until the keyboard associated with set B has been set) by the opening of contact 335. If both sets A and B are in use when the switch 251 is searching, the circuit of the test relay 213 will be completed in one of the positions 3, 6, 9, or 12 over contact 259, wire 396, relays 341, 342, contact 343 of switch 340 (individual to set C), front contact of relay 349 (energized over contact 321 when switch 310 of set A has reached its seventh position), and contact 335 of switch 330 (individual to set C) closed when this switch has reached its seventh position, i.e. when the keys have been depressed. In positions two to six of switch 340, the test circuits for the A and B sets are opened. Control of register by keyboard. If the keyboard is free when the switch 310 comes into its fifth position, the relay 401, Fig. 3, is de-energized and the switch continues its movement into its sixth position, in which the keyboard holding- magnets 402 are energized. When the operator has depressed a key in each series, the relay 401 is again energized and moves the switch 310 into its seventh position, in which the registers are set in accordance with the depressed keys. The register clutch magnets 411 - - 415 in parallel are energized in series with a relay 400, and rotate their respective registers under control of the test relays 405 - - 409. When the last register has come to rest, relay 400 de-energizes and moves the switch 310 into its tenth position, in which the holding-magnets 402 are de-energized so that the keyboard is made free for other calls. Control of first selector, Fig. 1, by register. In the system described, the final selectors are 200-point switches, the capacity of the exchange being 20,000 lines. Translation is therefore necessary as described in Specification 21259/11, and the register 411 serves only to control translation for the odd and even initial digit of the wanted number, which it will be assumed is 11319. In the tenth position of switch 310, the fundamental circuit is closed over relay 204, Fig. 1, contact 222, contact 255 (assuming the A-register set is in use), wire 391, stepping-relay 322, wire O, back contact of counting-relay 422, and wire 487, to earth over contact 323. The relay 204 moves the sequence switch 206 into its sixth position, in which the clutch magnet 223 of the tripping-spindle is energized. The rotation of the spindle short-circuits in the usual manner the stepping-relay 322, Fig. 2, which repeats the impulses over contact 363 top, wire 488, contact 431 top of register 412, contact 417 bottom of register 411, wire 471, to the counting- relays 424, 425, &c. The counting-relays operate in known manner, and after the tripping- spindle has rotated the desired number of steps, in this case one, the relays 422, 426 are energized, relay 422 opening the fundamental circuit to cause relay 204 to move the switch 206 into its seventh position, in which an idle second selector is found, and relay 426 earthing lead 490 to move switch 310 into its twelfth position. As the switch 310 leaves its tenth position, the holding-circuit of the counting-relays is opened at contact 318 and then at contact 326, the introduction of the resistance 327 reducing sparking. Hunting operation of first selector. In the seventh position of switch 206, the brush-carriage clutch magnet 240 is energized over contact 211 and rotates the brushes until an idle second selector is found, when the test relay 213 is energized over its right-hand winding and closes a circuit for the second test relay 212 which opencircuits the clutch magnet 240 and moves the sequence switch into its ninth position. Control of further selection by A-operator. The switch 206 remains in its ninth position until the A-operator inserts the plug in the jack of the assigned junction, thereby energizing relays 230, 231, 233, 229. Relay 229 moves the switch 206 into its tenth position, in which the fundamental circuit is extended to the second selector, Fig 4, over contacts 236, 237 and bushes 238, 239. Second selector. The relay 504 moves the sequence switch 510 into its second position, in which the tripping-spindle 520 is set in the usual manner under the control of the thousands and hundreds registers 412, 413 in the twelfth position of the register sequence switch 310. When the spindle has been set to the desired position, the sequnce switch 310 is moved to its fourteenth position and the fundamental circuit is opened, whereupon relay 504 moves the switch 510 into its third position, in which the brush carriage is rotated under control of a first test relay 513, which, when an idle final selector is found, energizes a second test relay 512 which arrests the brush carriage and moves the switch 510 into its sixth position, wherein the left-hand winding of the test relay 513 is directly earthed and the fundamental circuit is extended to the final selector. Final selector. The relay 544, energized